/* Modern Premium Design System */
:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: rgba(30, 41, 59, 0.7);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-primary: #3b82f6; /* Blue */
    --accent-secondary: #10b981; /* Green */
    --accent-danger: #ef4444;
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    background-image: 
        radial-gradient(at 0% 0%, rgba(59, 130, 246, 0.15) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(16, 185, 129, 0.15) 0px, transparent 50%);
    background-attachment: fixed;
}

/* Typography */
h1, h2, h3, h4 {
    font-weight: 700;
    letter-spacing: -0.025em;
    color: var(--text-primary);
}

/* Layout & Container */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    padding-bottom: 80px; /* Space for bottom nav if needed */
}

/* Glassmorphism Cards */
.card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 24px;
    margin-bottom: 20px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--glass-shadow);
    border-color: rgba(255, 255, 255, 0.2);
}

/* Auth Section */
.auth-container {
    max-width: 400px;
    margin: 10vh auto;
    text-align: center;
}

.auth-header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Forms & Inputs */
input, select, textarea {
    width: 100%;
    padding: 12px 16px;
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition);
    margin-bottom: 12px;
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
    background: rgba(15, 23, 42, 0.8);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    gap: 8px;
    font-size: 1rem;
    width: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary), #2563eb);
    color: white;
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(59, 130, 246, 0.4);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
}

.btn-google {
    background: white;
    color: #1f2937;
    margin-bottom: 16px;
}

.btn-google:hover {
    background: #f3f4f6;
}

/* Header & Navigation */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    padding: 16px;
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    border-radius: 16px;
    border: 1px solid var(--glass-border);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 12px;
}

.avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    color: white;
}

/* Controls Section */
.controls-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 24px;
}

@media (max-width: 600px) {
    .controls-grid {
        grid-template-columns: 1fr;
    }
}

/* Exercise List */
.exercise-card {
    background: rgba(30, 41, 59, 0.4);
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 16px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.exercise-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent-primary);
}

.exercise-meta {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 4px;
}

/* Sets Grid */
.sets-container {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.set-row {
    display: grid;
    grid-template-columns: 40px 1fr 1fr 40px;
    gap: 12px;
    align-items: center;
}

.set-number {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.set-input {
    margin-bottom: 0;
    text-align: center;
    font-variant-numeric: tabular-nums;
}

.set-input.previous {
    border-color: transparent;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-secondary);
}

.set-input.current {
    border-color: var(--accent-primary);
    background: rgba(59, 130, 246, 0.1);
    color: var(--text-primary);
}

.btn-icon {
    width: 32px;
    height: 32px;
    padding: 0;
    border-radius: 8px;
    background: rgba(239, 68, 68, 0.1);
    color: var(--accent-danger);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-icon:hover {
    background: rgba(239, 68, 68, 0.2);
}

/* Tips & Notes */
.tips-box {
    margin-top: 12px;
    padding: 12px;
    background: rgba(16, 185, 129, 0.1);
    border-radius: 8px;
    border-left: 3px solid var(--accent-secondary);
}

.tips-title {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--accent-secondary);
    margin-bottom: 4px;
    text-transform: uppercase;
}

.tips-content {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Utilities */
.hidden {
    display: none !important;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(59, 130, 246, 0.3);
    border-radius: 50%;
    border-top-color: var(--accent-primary);
    animation: spin 1s ease-in-out infinite;
    margin: 40px auto;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.save-toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background: var(--accent-secondary);
    color: #000;
    padding: 12px 24px;
    border-radius: 50px;
    font-weight: 600;
    box-shadow: 0 10px 15px -3px rgba(16, 185, 129, 0.4);
    transform: translateY(100px);
    opacity: 0;
    transition: var(--transition);
    z-index: 100;
}

.save-toast.show {
    transform: translateY(0);
    opacity: 1;
}

/* Chart Customization */
canvas {
    width: 100% !important;
    height: auto !important;
}